1) Field of the Invention
The present invention relates to a technology for forming a photomask.
2) Description of the Related Art
Conventionally, when forming a pattern (e.g., herringbone grooves or the like) on a surface of a workpiece (e.g., a shaft, a bearing, or the like), one approach is to form an electrode having a shape corresponding to the pattern and transfer the electrode by electrolytic processing or electric discharge machining or the like.
This approach requires provision of a gap, for flow of the working fluid, between the electrode and the workpiece, moreover, the workpiece is not masked, so that setting optimal electrolysis conditions or electric discharge conditions becomes a difficult task. In addition, the electrode gets worn.
As a countermeasure, Japanese Patent Application Laid-open No. H5-191015 discloses a technique of forming a coat of a light non-transmitive layer and photo sensitive resin on a surface of the workpiece, exposing the coat with the mask, and developing and removing portions that are not exposed.
Japanese Patent Application Laid-open No. S63-144888 discloses a technique of efficiently raising over a broad range the temperature of a photo sensitive resin or the like Laser light or plural prisms or the like are used to achieve this effect.
Japanese Patent Application Laid-open No. S56-41639 discloses a technique of using an elastic material to have tight and close bonding between a mask and a photo sensitive resin or the like. With this arrangement, exposure can be carried out easily.
However, efficiency in forming the mask pattern is poor in the conventional techniques.
Specifically, the mask cannot be replaced easily because it is fixed to a supporting portion. If the workpiece has plural surfaces, and if the surfaces have various shapes, then a lot of time is wasted in replacing the mask, it puts a great burden on the person who performs the replacement.